English verb conjugation
COULD RUIN

Regular verb: ruin - ruined - ruined

Affirmation

Simple form	V-ing form
I could ruin you could ruin he could ruin we could ruin you could ruin they could ruin	I could be ruining you could be ruining he could be ruining we could be ruining you could be ruining they could be ruining
Perfect	V-ing perfect
I could have ruined you could have ruined he could have ruined we could have ruined you could have ruined they could have ruined	I could have been ruining you could have been ruining he could have been ruining we could have been ruining you could have been ruining they could have been ruining

Negation

Simple form	V-ing form
I couldn't ruin you couldn't ruin he couldn't ruin we couldn't ruin you couldn't ruin they couldn't ruin	I couldn't be ruining you couldn't be ruining he couldn't be ruining we couldn't be ruining you couldn't be ruining they couldn't be ruining
Perfect	V-ing perfect
I couldn't have ruined you couldn't have ruined he couldn't have ruined we couldn't have ruined you couldn't have ruined they couldn't have ruined	I couldn't have been ruining you couldn't have been ruining he couldn't have been ruining we couldn't have been ruining you couldn't have been ruining they couldn't have been ruining

Interrogative form

Simple form	V-ing form
could I ruin? could you ruin? could he ruin? could we ruin? could you ruin? could they ruin?	could I be ruining? could you be ruining? could he be ruining? could we be ruining? could you be ruining? could they be ruining?
Perfect	V-ing perfect
could I have ruined? could you have ruined? could he have ruined? could we have ruined? could you have ruined? could they have ruined?	could I have been ruining? could you have been ruining? could he have been ruining? could we have been ruining? could you have been ruining? could they have been ruining?

Interro-negative form

Simple form	V-ing form
couldn't I ruin? couldn't you ruin? couldn't he ruin? couldn't we ruin? couldn't you ruin? couldn't they ruin?	couldn't I be ruining? couldn't you be ruining? couldn't he be ruining? couldn't we be ruining? couldn't you be ruining? couldn't they be ruining?
Perfect	V-ing perfect
couldn't I have ruined? couldn't you have ruined? couldn't he have ruined? couldn't we have ruined? couldn't you have ruined? couldn't they have ruined?	couldn't I have been ruining? couldn't you have been ruining? couldn't he have been ruining? couldn't we have been ruining? couldn't you have been ruining? couldn't they have been ruining?